Connecting better speaker by cable to Dot

Any speakers will work. There aren't speakers that are better for the dot than they are for other devices. Try a NAD 7225PE amp with a pair of Mirage 360 speakers. That's my setup, and I think it sounds great. The dot has 3.5 mm jack audio out, which can plugged directly into most powered speakers, but if you have an amp+speakers, you likely need a 3.5mm to RCA cable, which is about $5. The full size echo doesn't have a 3.5mm out, so your stuck with the built in speakers. I don't understand the part about "If I get it set up by cable, (external speaker) will it convert to only the nice stereo speaker take over, or will have I have both on at same time?" Are you asking if the speaker built into the dot will play while you have external speakers plugged in? If that is the case, than no, the built in speaker will not play, but the stereo ones will. Hope this helps!